1. Field of the Invention
The present invention generally relates to a router apparatus used in a network. More specifically, the present invention is directed to such a router apparatus equipped with a routing table managing processor capable of rapidly recovering a network communication when a failure happens to occur in the network.
2. Description of the Related Art
In networks, large amounts of routing information are continuously communicated, and storage contents of routing tables are rewritten within huge numbers of routers from time to time.
Actually, communications are sometimes, suddenly interrupted because table contents are mistakenly rewritten by network operators, and furthermore, communication failures will occur due to illegal actions by network operators.
There is another problem that communication failures occur which are caused by not only own router, but also routers of third parties, while networks become more complex and highly advanced.
Once such a communication failure, or problem happens to occur, a first action should be taken to rapidly recover the interrupted communication prior to fact finding action.
However, since the conventional router apparatus has only one routing table, failure preventive characteristic of this router apparatus is deteriorated. As a result, such a conventional router apparatus has problems in that lengthy time is necessarily required when the failure occurs and thereafter the interrupted communication can be recovered, and furthermore, the reason why such a failure happens to occur cannot be easily investigated.
To avoid these problems, in a certain network, a plurality of router apparatuses are often arranged. However, even if those treatments are taken, when such a communication failure is caused by the routing table itself, such a communication failure still occurs.
The present invention has been made to solve the above-explained problems, and therefore, has an object of the invention to provide a router apparatus capable of rapidly recovering an interrupted communication when a communication failure happens to occur.
To achieve the above-explained object, a router apparatus, according to an aspect of the present invention, is characterized by comprising: a plurality of routing tables into which new route information is stored every time route information is changed; a rewriting time saving unit for saving rewriting time information of the plurality of routing tables; a table switching unit for switching the plurality of routing tables; and a route processor nit for managing, for example, setting/rewriting/deleting the routing table based upon route information supplied by a network operator, or route information obtained from routing protocol, wherein when a communication failure caused by the routing table occurs, the failed routing table is switched to another routing table into which old route information has been stored so as to continue the communication, and also, a communication failure reason is investigated by comparing the route information before/after the failed routing table is switched.
Also, the present invention provides such a router apparatus, characterized in that the old route information is the latest route information.
Also, the present invention is characterized in that only difference information is stored into the plurality of routing tables.
The normal router apparatus is equipped with only one routing table for storing thereinto route information, whereas the router apparatus of the present invention is characterized in that both old route information and new route information are simultaneously saved.
In the case that a communication failure happens to occur which may be predicted by such a reason that a content of a routing table is updated, the router apparatus immediately returns the new route information to the old route information so as to recover the present communication. Accordingly, the failure occurrence time can be reduced.
Also, since the old condition is saved, it can be easily compared with the failure condition, which may readily contribute to the investigation of the failure reason.